Fixes orbiting a deleted atom sending you to null space

This also handles the garbage collection issues. As far as i'm concerned, if its been qdeled, but loc isn't null, it's fair game for orbits.

code/__HELPERS/unsorted.dm

@@ -1432,7 +1432,7 @@ B --><-- A
 	var/angle = 0
 	var/matrix/initial_transform = matrix(transform)
 	spawn
-		while(orbiting)
+		while(orbiting && orbiting.loc)
 			loc = orbiting.loc
 
 			angle += angle_increment